Fig. 4. Potential mechanisms for how Rho proteins could regulate aspects of the microtubule cytoskeleton. (a) Stable, detyrosinated microtubules (purple) are induced by RhoA. (b) RhoA might also cause the phosphorylation of microtubule-associated proteins and thus destabilize microtubules. (c) Rac1 and Cdc42Hs might decrease the microtubule catastrophe frequency and thus promote microtubule growth through Pak1-dependent phosphorylation of stathmin/Op18. (d) Cdc42Hs activity is required for the reorientation of the centrosome towards the direction of migration, which could occur through cortical cytoplasmic dynein activity.
